I've thrust about trying to decide what era Gammage House is set in. Finally I have a year - 1885. I'm still not sure why, but it had to be a) significantly after the Civil War, b) early enough that decorative painting and other early 1800's details wouldn't have been replaced or painted over c) early enough that the Seamaster father could be remembered by his daughters, but that they might not have preserved his bedroom . There is just not enough space in this house for the father's bedroom!!! My story is that when he was alive, the girls shared a room.
The great thing about dollhouses which are clearly dollhouses (not models or miniatures of specific periods) is that a little fuzzy math doesn't hurt. Or a little fuzzy history as this seems to be.